Production of bast fibers for papermaking and other purposes



Patented Mar. 26, 1935 p 995,509} i I I PRODUCTION OF EAST FIBERS F PAPER;

' MAKING AND OTHER PURPOSES I George A. Richter, Berlin, N111. assi'g'nor to Brown, Company;

of Maine No Drawing.

3 7 Claims;

- This invention relates to the production of bast fibers or least fiber pulp for. paper-making and other purposes, including the manufacture of yarns and textile fabrics. I f

There are various vegetableplants like, ramie, hemp and flax, which bear so -called bast fibers, that is, fibers which occur as the external-or sur-' face layer of the plant stalks and which extend for ;the entire length of the stalks. The hast 10 fibers are characterized by their excellentphysical and chemical qualities, whereas the'rest of the fibers are of a comparatively short length and of a distinctly lower order of quality The oldject'of. the present invention is the" segregation of the bast fibers in an" advantageous condition from the short fibers so that the bast fiber portion may serve for thcse purposes to'which-it is best adapted, and the short fiber 'portionrnay serve in other connections-forwhich it ismost useful. In accordance with the pre'sentinvention,stalks of the foregoing character are first cut' across their longitudinalaxes into chips or cylin drical pieces of a length commensurate with the' fiber length desired in the long fiber portion to be segregatedand recovered from themass of mixed fibers into which the stalks can be resolved. The chips are then subjected'to the fiber-liberating action of a suitable chemical pulping or cooking liquor, for instance, an'alka-line cooking liquor such' as is used in the-production of so-called' 'kraft or soda pulps'or'anacid cookingliquor such as is employed intheprdductibn of so called-- sulphite pulp. The chemical pulp thereby pro duced consists of a mass of fibers made up or .the comparatively long bast: fibers and: the shorter fibers originating inithe internal: structure of the stalks. The longer bast fibers are distinguishable chemically from the shorter fibers: in; that, in'the= case of 'r'amie, for example, they-are of lower pentosanand lignincontent thanthe short fibers. Even when out to short length-as bybeati'ng action preparatory to paper-making, the bast fibers show physical distinctions,v which are observable under the microscope; from" the short fibers 'de+ rived from the internal structure of the ramie 45 stalk. In-accordance with my i'nventionythe bast fiber-portion of the jchemicalipulp is separated practically in entirety from thelshort fibered poi.- tion through the use of suitableapparatus; ior'instance, apparatus of the typedisclosed 'inU. S. Patent No:"1;786,973',l-issued December 30, 1930- to Robert A. Webber. .Apparatu's such "as is dis-. closed in that .patent is designed to select; and remove the long fibered portion o-fa pulp through the action ,of-'edgespresenting"members, e. g.,-{ grills, which, as'th'ey 'ar'e-jmoved" through a pulp suspension of .the'appropriate consistency, pick up the long. fibers. while by-passing the short ones. Such! anapparamsnsof particular value in selecting or segregating the long 'bast 'fiber porents are largely Berlin, N HZ, a corporation I '1 Application December 28,1932, w Serial No. 649,154; I

tion "or:- a; pulpliberated from 'ramie b simuar 'f stalks because the best fibers are distinctly longer.

than the rest of the pulp and little, if any, bast fiber is missed'by the selecting apparatus even.

when thefpulp is passed through the apparatus only once.

Let us assume-,ior example; that'thebfiginal stalks are chopped or 'cut into chips whoseulengthapproximate about one-half inch. In somecases, it may be-des'irable-to. debark the-stalks or chips;

so as to promote subsequent fiber-libe-ratingactionfasiwel-l' aslto enhancethe cleanliness of the liberated-fibers or pulp; The. chips can be subjected under fiber-liberatingyconditions to the;

action of a: kraft cooking. liquor which-as is well known, contains caustic soda and sodium sulphide asthe fiber-liberating chemicals. "If desired; the" cooking liquor may be 'a soda liquor, that is, 'one containing substantially only caustiosoda :as' the fiber-liberatingchemical; An acid cooking liquor such asasulphurousacidsolutiorl of ,calciumsulphite, sodium sulphite, or the] like; may ;be

used .toefiect the pulping ofthestalksu Indeed.

any suitable chemical pulping; liquor,. including a straight solution of, sodium sulphite, maybe used.

cementitious content of the stalks, thereby-Eben;

ating the ultimate fibers. of. whichythe stalksware composed. :The resultingpulpds .washedjfree of .f 3'0 -v able. selecting mechanism which; functionsato 3 chemical cooking liquorqand 'isput through suit.-

segregate the best fiber portion',';which,- in-the in the. caseofrramie bear about 10%. by-weight of bast :fiber, the rest-cithestalk onsistin of the short fibered interiorportion, pith, and cee" liquor.

mentitious material, which-latter, two constituw dissolved in the chemical pulping 1 short fibered-portion'is more easily bleachable to whiteness than the shortfiberedfportion.A Inth'e case of stalkswhich have been, pulped in an acid sulphite orsimilar cooking liquor, the longfibered bast portionneeds little, .if "any, bleaching to. bee; come white. "In ia'ct,: the'long fiberedjbastpor-J tion may be used. in the condition that it issepa rated from the pulp mass as a whole,'that.

without bleaching, for paper-making. find. for the;

yields papers ofh'igh st1'eng'th,-;toughness," and other physical characteristics. Such papers are Io i 251 under conditionsyto dissolvefthe;-encrusting ,or

similar in their characteristics to high grade rag or linen papers ashretofore made. -The short fibered portion may, after bleaching. or other suitable chemical treatment, serve as a constituent in papers of comparatively low quality, e. g., book or magazine papers, such as heretofore made from comparable short fibered pulps such as soda pulp. Either the long fiberedqorshortfibered portions may be subjectedto refinement in alkaline liquors and/or to bleaching treatment, if de-' 'sired; or the pulpas a whole may undergo such processing before it'. is classified or graded into its long fibered and short fibered components;-

It is, however, preferable to treat 'eachfiber portion'indepen'dently, for, as hereinbefore indi-- cated, the two portions respond differently to chemical treatment and are best adapted for different purposes, which usually require diiferent chemical conditioning treatments for the fiber. In someinstances, .the raw stalks may be exposed totheaction of. chlorine water, hypochlorite liquors, or similar oxidants, which extract ligneous and other undesirable constituents from the raw stalks or promote their dissolutionin'the chemi substantially dry' fibers.

calcooking liquorto which the stalks are subse- 7 quently subjected J h It is'of coursepossible to cause-chemical pulping of the whole stalks, but in such case one encounters the difiiculty :01 :producing. such long bast fibers that theyftend to become so badly.

of the appropriate length" before they chemical pulping operation. When the separated, long fibered bast portion is to serve in textile-making 45,.

operations, the chips may be of a lengthof, say 1 to 3 inches, as fibers'of such length can be readily carded, combed, spun, twisted, and otherwise treated like cotton fiber. When this portion is to enterinto paper-making operations, or is to be formed into rovings or yarns through the furlingof damp pulp ribbonsproduced on machinery up inthe stalks, across their longitudinal axes fiber length of wood pulp, cooking such chips in o'f'the paper-makingtype, or through the twisting ofpaper strips,the chips may be of a length v I of, such fibers consistingof both. the long bast or, say one-half to one inch, that is, of a'length distinctly greater than the average fiber length. of wood pulp but not unduly long, as otherwise, it would be necessary to expend considerable'en ergy in the beater engine in reducing the fibers to satisfactory paper-making length. The fact thatfthe fibers are of a markedly greater length than wood pulp fibers means that even after beating has been effected and the pulp hasbeen hydrated to highly satisfactory paper-making condition, the length of the fibers is such that the papers made therefrom are-characterized by their extraordinary toughness, strength, tear resistance, rattle, and other valuable'qualities associated with r'agand linen papers of the best grade. I ,claim:+ 1 e 1. A process which comprises cutting bast fiber-bearing stalks. all'of whose-fiber is bound into chips of a length greater than the average a chemical liquor to liberate the ,fibersfthereof, such fibers consisting of. both long {bast fibers and short stalk fibers, and selectively removing long bast fibers from the rest of the stalk fibers. 2. A process which comprises cutting bast fiher-bearing stalks,fall of whose fiberv is bound up in the stalks, across their longitudinal axes intochips of a length of at least about one-half to liberate the fibers thereof, suchfibersconsisting of both long bastfibers and short stalk fibers and-selectively removing the bast fibers having a length of at least about one-half inch from the rest of the stalkfibers; j g

l 3. A process which comprises cutting bast fiber-bearingstalks, allof whose fiber'is bound up in the stalks;=.across; their longitudinal axes into chipsfof' a'length greater than the average fiber length of wood pulp, cooking such chips in a cheniicalliquor to liberate the fibers thereof,

such, fibers consisting of both long bast fibersand short stalk fibers, selectivelyremoving the long bast fibers from the-rest of the stalk fibers, beat- I ingsaid removed bast fiber portion, and forming said beaten fiber portion intopaper;

' 4. A process which comprisescutting bast fiber-bearing stalks, all of whose fiber'is' bound up in the stalks, across their longitudinal axes into chips of a length ranging from iabroutzonehalf inch to about three inches, cooking .such chips in a chemical liquor to liberatethe fibers thereof, such fibers consisting of both long bast fibers and short stalk fibers; and selectivelyremovingthe bast fibers having a length ranging from about one-half inch to about three inches from the rest'of the stalk fibers. i

, 5. A. process which comprises cutting :bast fiber-bearing stalks, all of whose fiber is bound up in the stalks, across. their longitudinal axes into chips of a length ranging from about one: half inch to about threeinches,cooking such chipsin a chemical liquor to liberate the; fibers thereof, such fibers consisting of both long bast fibers and short stalk fibers, washing the mixed fibers, and selectively removing the bast-fibers having a length ranging from about one-half inch to aboutthree inchesfrom the rest of the 6. A process which comprisesicutting' stalks across their. longitudinal'axes' into chips of a length ranging from aboutgone-half inch to about three inches, cooking such chips in a chemicalliquor to liberate all the fibers there'- fibers and'the short stalk fibers'havingan' average length of only about one-sixteenth inch,

stalks across their longitudinal axes intoflchips inch, cooking such, chips in a chemical liquor of a length ranging from about one-half inch r to about three inches, 'cooki'ng'such' chip's in'a chemical, liquor to liberate all the" fibers there-' of, such fibers consisting "of'both the long best,

fibers and the short-stalkifibers having an a'veragelen'gthof only about one-sixteenthfinch,

' washing the mixed' fibers, and selectively 'removing the bastfibers havingua. length; ranging from .the rest or the stalk fibers.

from about one-halfinch to about inches GEORGE A. 

